Concrete holding mixer

ABSTRACT

A concrete mixer is adapted for use as a temporary concrete holding drum by providing a conveyor for charging the mixer drum with premixed concrete for holding or discharge directly to the mixer discharge chute. The entire unit is transportable and the conveyor is separately demountable therefrom such that the mixer may be operated as a conventional transit mixer.

United States Patent Inventors Robert W. McKillop Milwaukee; WilliamStanis, Muskego, both 01 Wis. Appl. No. 39,495 Filed May 21, 1970Patented Oct. 12, 1971 Assignee Rex Chainbelt Inc.

Milwaukee, Wis.

CONCRETE HOLDING MIXER 6 Claims, 1 Drawing Fig.

US. Cl 259/161, 259/177 Int. Cl B28c 7/00 Field of Search 259/ 161162,164,165,160,169,l70,172,l75, 176,177, 153, l4,30;214/630 [56]References Cited UNITED STATES PATENTS 2,357,583 9/1944 Franco 214/6303,038,705 6/1962 McDermott.. 259/175 3,185,450 5/1965 Duecy 259/1723,526,392 9/1970 Buelow 259/161 X Primary ExaminerRobert W. JenkinsAttorneysErnst W. Schultz and Joseph J. Jochman, Jr.

ABSTRACT: A concrete mixer is adapted for use as a temporary concreteholding drum by providing a conveyor for charging the mixer drum withpremixed concrete for holding or discharge directly to the mixerdischarge chute. The entire unit is transportable and the conveyor isseparately demountable therefrom such that the mixer may be operated asa C011- ventional transit mixer.

PATENTED um I 2 I97! @yoberyggiz/ a lyornqrq CONCRETE HOLDING MIXERBACKGROUND OF THE INVENTION 1. Field of the Invention The presentinvention pertains to the art of concrete delivery and placement, andmore particularly to a concreteholding means for use intermediate thedelivery of readymixed concrete to a construction site and its finalplacement. The concrete-holding means includes a concrete mixer fed by abelt conveyor and adapted to receive the supply of concrete delivered tothe site, such as by truck mixers, and to accommodate surges in suchsupply, and to simultaneously provide a discharge of concrete for finalplacement either continuously or intermittently, as required.

2. Description of the Prior Art.

The supply of concrete to the location of the construction of a buildingor other structure is often provided by transit-type concrete mixers or,as they are more commonly known, truck mixers. The advantages ofsupplying ready-mixed concrete are well known and include elimination ofon-site concrete batching and storage of raw materials.

It is often difficult, however, to coordinate the actual placement ofconcrete in the structure with the supply of readymixed concrete beingdelivered by a fleet of truck mixers. Thus, a slowdown or unexpectedhalt in the placement or pouring of concrete may cause a backup of truckmixers waiting to discharge concrete. Such a delay is very costly to theconcrete supplier who is largely dependent on the number of trips eachtruck mixer makes. In addition, a backup of trucks can interfere withoperations at the construction site and, particularly in metropolitanareas, can impede the flow of local traffic and create traffic hazards.

The rate at which concrete is being poured may, at times, exceed thedelivery rate. This problem often occurs or is compounded when the truckmixers are required to be maneuvered into restricted or otherdifficult-to-reach positions be fore discharging the concrete. Theresult is, of course, delays in the final placement of concrete.

Various devices adapted to facilitate the handling and placement ofconcrete are shown in the prior art. It is, thus, known to provide atemporary storage or holding bunker which receives ready-mixed concretefrom truck mixers and form which portions may be selectively withdrawnand elevated for placement. This apparatus is shown in U.S. Pat. No.2,357,583 and was developed for use with construction methods andequipment in which elevators operating in towers erected at the job siteare used to lift concrete for placement.

The above identified patent had as a primary object the solution of theproblem caused by the difficulty in coordinating the delivery and finalplacement of ready-mixed concrete, as previously discussed. The systemand apparatus disclosed therein were of limited general utility and ofcomplex construction, and have been replaced by simpler and more rapidmeans of elevating concrete for placement. The problem of coordinationbetween delivery and placement, however, has remained and nosatisfactory solution has been found for use with modern methods andapparatus; and the problem is, of course, not limited to situationswhere delivered concrete must be elevated for placement, but exists inany construction job where the ready-mixed concrete must be poured in aplace inaccessible to the truck mixer and/or where the demand may beerratic or a continuous supply critically necessary.

It is common today, in building large concrete structures of variouskinds, to move concrete from the point of delivery directly to placementby means of a bucket suspended from the boom of a crane. This method hasgained wide acceptance because of its versatility and the utilization ofequipment commonly employed in various other operations on theconstruction site. Truck mixers discharge concrete directly into thebucket which generally can be filled a half dozen or more times from anaverage capacity mixer. The truck mixer must, therefore, await thereturn of the bucket each time with the consequent loss of considerabletruck time. On the other hand, if the truck mixers must back orotherwise move one at a time into a restricted position to unload, as isoften the case, considerable pouring time may also be lost while theempty truck is leaving and the next one is moving into position tounload.

Another commonly used means of moving concrete from the place ofdelivery to remote placement in a structure is a concrete pump. Aconcrete pump is generally fed by a relatively small hopper mounted onthe unit and, as is known in the art, an uninterrupted even flow ofconcrete supplied to the hopper is very critical.

Belt conveyors are also often used to carry concrete to placement inremote areas of a job site. In this placement method, it is equallyimportant to be able to maintain a continuous supply of concrete to thebelt conveyor and to be able to halt the supply if final placement isstopped for any reason.

It is, therefore, apparent that the ideal delivery-placement systemwould include an intermediate concrete holding means wherein the supplythereto could be made completely independently of the dischargetherefrom. It is also important, as is known and disclosed in the priorart, that concrete held in place for more than short periods be mixed oragitated to maintain uniformity in the mix and avoid segregation of theingredients.

U.S. Pat. No. 3,185,450 shows a mobile apparatus adapted to receive anddistribute a concrete mixiThe apparatus includes a mixing skip feeding abelt conveyor which, in turn, discharges into a chute for finalplacement. Though designed primarily for mobile placement of concrete,this type of device could also be used as a stationary intermediary forthe receipt of concrete from a truck mixer and the selectiveredistribution for placement either directly or by a bucket or othermeans. A

- particularly critical disadvantage, however, exists in the inabilityof this device, as disclosed, to simultaneously receive and dischargeconcrete, as required in order to avoid the costly delays describedabove.

A portion of the concrete batch plant shown in U.S. Pat. No. 3,446,487includes a horizontal mixer fed by a belt conveyor. This combinationprovides a disclosed ability for selective or simultaneous charging anddischarging with temporary holding and mixing in the horizontal drum.This mixer, however, is designed particularly for use in a batch plant,and the elaborate concrete transfer mechanism is specifically adaptedfor operation as part of the batching system. The horizontal mixer is,thus, not readily adaptable to operation outside the system for which itwas designed. Additionally, its cost may exceed by as much as four timesthe cost of a mixer of the type used on a truck mixer, and itsmodification for limited use outside a batch plant would be economicallyimpractical.

SUMMARY OF THE INVENTION In the present invention, a conventionalinclined axis concrete mixer provides a temporary holding and mixingstation to minimize the adverse effects of unavoidable lack ofcoordination between the supply of ready-mixed concrete to theconstruction site and its final placement in the structure. Concrete issupplied to the charging hopper of the mixer by a belt conveyorextending from a substantially low level at the head end of the mixerover and in closely-spaced relation to the top of the drum, andterminating over the hopper.

One truck mixer can discharge its full load of concrete onto theconveyor without delay and move out of the way for the following truckmixer. The concrete is carried to the charging hopper of the stationarymixer, from which it is funneled into the mixer drum. The concrete maybe temporarily held and mixed in the drum or simultaneously dischargedby opposite rotation of the drum in a known manner.

The conventional transportable mounting of the mixer and conveyorprovides necessary portability and the conveyor is demountable therefromsuch that the remaining unit can be towed by a standard tractor andoperated as a transit mixer.

BRIEF DESCRIPTION OF THE DRAWING The drawing shows a side elevationalview of the concrete holding mixer in its preferred embodiment mountedon a semitrailer.

DESCRIPTION OF THE PREFERRED EMBODIMENT In the drawing, a portableconcrete holding mixer includes a conventional inclined axis concretemixer 11 mounted on a semitrailer l2 and to which concrete is suppliedby a belt conveyor 13 mounted atop the mixer 11.

The mixer drum 14 is a frustoconical inclined axis type supported at itsforward and rearward ends for rotation about its axis. The forward orhead end is supported by a pedestal 15 and the rearward end by a rearupright frame member 16. The pedestal l5 and upright frame member 16 arefixed, respectively, to the forward and rearward ends of a pair oflongitudinal frame members 17 which are, in turn, secured to the trailerchassis 18.

The drum 14 is driven by an annular drum sprocket l9 fixed to the outerperiphery of the drum. A drive chain 20 interconnects the drum sprocket19 and a drive sprocket 21. The drive sprocket is powered through aspeed reducer 22 and either a mechanical or hydraulic transmission 23 byan engine 24 mounted on the trailer chassis 18 forwardly of the pedestal15.

Concrete (or a batch of concrete ingredients) is supplied to the mixerdrum 14 through a charging hopper 25 disposed adjacent the open rearwardend of the drum. The hopper is constructed and positioned to funnel theconcrete down and into the interior of the drum. As is well known in theart, the interior drum wall is provided with a spiral mixing anddischarge blade 26. When the drum is rotated in one direction, the bladecarries the concrete to the closed head end of the drum, and rotation ofthe drum in the opposite direction moves the concrete upwardly andrearwardly where it is discharged over the lip 27 defining the open endof the drum.

A discharge chute 28 is attached by means of a vertical axis pivot 40 tothe upright frame member 16 such that its upper receiving end is alwayspositioned directly below the discharge hopper 39 and the lip 27 of thedrum for the receipt of concrete discharged therefrom. The chute 28directs the concrete by gravity either to final placement or to areceiving means such as a bucket B by which the concrete may be moved toa location not accessible for direct placement from a mixer.

The belt conveyor 13 is of common construction and includes a pair ofsiderails 29 between and at the ends of which are mounted the head andtail pulleys 30 and 31, respectively. A conveyor belt 32 is trainedabout the pulleys 30 and 31 and operates therebetween over a series ofspaced troughing idlers (not shown) in a manner well known in the art.The head pulley 30 is used to drive the belt and may, in turn, be drivenby the engine 24 or a separate power source in a conventional manner. Itis also known to drive the belt through the tail pulley 31.

The head pulley 30 is positioned over the charging hopper 25 and theconveyor extends forwardly over the top of the mixer 11 and curvesdownwardly over the head end of the drum l4 and engine 24. The forwardcharging end of the conveyor 13 lies just forwardly of the trailerchassis l8 and is provided with a receiving hopper 33 disposedsufficiently low to be reached by the chute C of a truck mixer or thelike.

The conveyor 13 is secured in position at its head end by attachment ofthe side rails 29 to extensions 34 of the upright frame members 16 oneither side of the drum. Similar vertical extensions 35 extendingupwardly from the pedestal l5 rigidly support the opposite end of theconveyor. The conveyor is preferably demountably secured to theextensions 34 and 35 for reasons which will be set forth below.

The semitrailer 12 is provided with tandem dual wheels 36 at the rearand a kingpin or fifth wheel 37 at the forward end for towing attachmentto a truck tractor (not shown). The forward end of the trailer may alsobe provided with suitable legs 38 or other means of stabilization andsupport when disconnected from the towing vehicle.

In operation, the portable concrete-holding mixer 10 is towed to aconstruction site and positioned where the receiving hopper 33 can bemost readily reached by the chute C of a truck mixer delivering concreteto the job site. Ideally, the hopper 33 will be positioned such that thetruck mixers can move directly to and away from the point of dischargewithout the necessity of backing or otherwise maneuvering into positionto reach it.

The discharge end of the holding mixer 10 is conveniently located to bereached by the bucket B or other means adapted to receive concrete fromthe discharge chute 28. The chute 28 may, of course, be provided withone or more extensionv sections, as required, and the pivotability ofthe chute may, in some instances, make direct final placement therefromfeasible.

. A truck mixer can discharge its entire load of concrete into thehopper 33 in one continuous operation. The conveyor belt 32 carries theconcrete to the charging hopper 25 through which it is funneled to theinterior of the drum 14. The drum may be rotating in either thedirection for holding and mixing or the direction for dischargedepending on the immediate requirements of concrete for placement. Ifthe former, the concrete will be moved forwardly by the spiral blade 26and accumulated in the larger and lower forward end of the drum 14. Thedrum capacity is preferably greater than the capacity of the averagetruck mixer delivering concrete, with 9 to 10 cubic yards being apractical minimum capacity. In this manner, a halt or temporary delay inpouring will not effect any corresponding delay in the discharge ofconcrete from the truck mixer.

If the drum 14 is rotated in the opposite direction, the blade 26 willmove the concrete upwardly and rearwardly to discharge over the lip 27surrounding the open drum end. The rate of discharge may be varied bycontrol of the speed of rotation in a known manner. A supply of concretein the drum l4 ensures the availability of concrete despite a temporaryhalt in the supply thereto, which may be occasioned by the deliveryvehicles being delayed en route or at the construction site.

The receiving end 41 of the conveyor 13, including the receiving hopper33, which extends beyond the forward end of the trailer 12 isretractable for transport or to allow truck mixers or other equipment tomove past as may be required for effective operation in a confined area.The receiving end may be attached by a pivot 42 to the remainder of theconveyor 13, and may include a power-operated retracting means (notshown). A substantial portion of the conveyor, including the siderailsand idlers, is, however, preferably constructed of aluminum or otherlightweight materials, whereby manual retraction of the receiving end 41is easily accomplished. The receiving end may also be designed totelescope into the remaining portion to effect retraction, in a mannerknown in the art.

The entire conveyor 13 is adapted to be demounted from its operativeposition secured to the mixer frame extensions 34 and 35. The conveyorsiderails 29 may be attached to the frame extensions 34 and 35 by meansof pinned connections 44 and 45, respectively, for rapid demounting.With the conveyor removed, the unit is a conventionalsemitrailer-mounted transit mixer and may be operated as such withoutany further modification.

Alternately, a slat conveyor or a screw conveyor, of a type well knownand commonly used to convey concrete, could be used in place of the beltconveyor 13. The mixer 11 and conveyor 13 could, as an alternateembodiment, be mounted on a standard chassis-cab unit, as mobileconcrete mixers most often are. A half-ca would be required for thisembodiment to provide space for the descending forward portion of theconveyor.

We claim:

1. In combination with a concrete mixing drum rotatable about aninclined axis with an opening at its upper end for charging anddischarging materials, said drum being provided with inwardly extendingspiral blades terminating at said opening and a charging hopper feedinginto the central portion of the drum opening interiorly of said spiralblades;

an inclined belt conveyor arranged over said drum with its inclinationin the same direction as the axis of said drum, said belt conveyorhaving a head pulley arranged over said hopper to cause materialconveyed by the belt to discharge into the hopper, and a tail pulleyconveniently low to the ground to enable charging of the belt conveyorby a similar concrete mixer mounted on a delivery truck, or by othermeans;

and means for rotating the drum and driving the belt conveyor so thatmaterials in the drum are discharged through the opening simultaneouslywith the feeding of material by the conveyor to the drum;

whereby the drum may be used to accommodate surges in supply of concretein excess of the desired rate of discharge of concrete from the mixingdrum.

2. A portable concrete mixer for temporary holding of mixed concretedelivered to a job site which comprises: a transportable frame, a powerdriven inclined conveyor carried by said frame and having a lower hopperdisposed to receive mixed concrete from a delivery vehicle and having anupper charging hopper, an inclined discharge chute carried by said frameso that its upper end remains effectively positioned beneath said hopperand so that its lower end may be variously positioned to deliver bygravity the concrete into a receiving bucket or the like positionedwithin the reach of the chute, and an inclined-axis power-drivenspiral-bladed concrete mixing drum carried by said frame and having itscharging and discharging opening disposed to receive the concretedischarging from said charging hopper and to deliver the same to saidchute as required whereby to provide temporary storage in the order ofone full load of a typical delivery vehicle so that the uninterruptedsupply of concrete to the job site is materially assured.

3. A portable concrete mixer unit for temporary holding of mixedconcrete delivered to a job site which comprises: a vehicle including aframe, wheels for transport to and ground-stabilizing legs forstationary positioning at the job site, a concrete mixing drum supportedby said frame for rotation on an inclined axis and having an upper openend at one end of the vehicle, said drum internally having spiral bladeswhich extend to said drum opening and define a smaller central chargingopening, power means carried vby the vehicle and connected to said drumto rotate the latter in one direction which causes the blades to pushthe drum contents to the lower closed end thereof and in the otherdirection to push the contents toward and out of the upper open endthereof, a charging hopper for said drum carried by said frame andhaving its spout extending into said smaller central opening of thedrum, an inclined power-driven conveyor carried by said vehicle frameand having a receiving hopper disposed at the other end of the vehicleto receive mixed concrete as from a delivery truck, said conveyorextending longitudinally over said drum and having its dischargetrajectory directed into said charging hopper, and an inclined dischargechute pivotally supported by said frame on a vertical axis beneath saidcharging hopper and drum opening so that its upper end remainspositioned to receive concrete therefrom and so that its lower end maybe variously positioned to deliver by gravity the concrete into areceiving bucket or the like positioned within reach of the chute.

4. The unit of claim 3 wherein the conveyor includes parallel frameextensions which support the receiving hopper beyond the end of thevehicle frame and said receiving hopper and the projecting portion ofthe conveyor are retractable as required for transport or to allowtrucks to move past the end of the unit.

5. The invention of claim 3 wherein the vehicle comprises a conventionalsemitrailer.

6. The invention of claim 3 wherein the conveyor is demountable fromsaid vehicle frame such that the unit may be used to deliver concrete asin the manner of a truck mixer.

1. In combination with a concrete mixing drum rotatable about aninclined axis with an opening at its upper end for charging anddischarging materials, said drum being provided with inwardly extendingspiral blades terminating at said opening and a charging hopper feedinginto the central portion of the drum opening interiorly of said spiralblades; an inclined belt conveyor arranged over said drum with itsinclination in the same direction as the axis of said drum, said beltconveyor having a head pulley arranged over said hopper to causematerial conveyed by the belt to discharge into the hopper, and a tailpulley conveniently low to the ground to enable charging of the beltconveyor by a similar concrete mixer mounted on a delivery truck, or byother means; and means for rotating the drum and driving the beltconveyor so that materials in the drum are discharged through theopening simultaneously with the feeding of material by the conveyor tothe drum; whereby the drum may be used to accommodate surges in supplyof concrete in excess of the desired rate of discharge of concrete fromthe mixing drum.
 2. A portable concrete mixer for temporary holding ofmixed concrete delivered to a job site which comprises: a transportableframe, a power driven inclined conveyor carried by said frame and havinga lower hopper disposed to receive mixed concrete from a deliveryvehicle and having an upper charging hopper, an inclined discharge chutecarried by said frame so that its upper end remains effectivelypositioned beneath said hopper and so that its lower end may bevariously positioned to deliver by gravity the concrete into a receivingbucket or the like positioned within the reach of the chute, and aninclined-axis power-driven spiral-bladed concrete mixing drum carried bysaid frame and having its charging and discharging opening disposed toreceive the concrete discharging from said charging hopper and todeliver the same to said chute as required whereby to provide temporarystorage in the order of one full load of a typical delivery vehicle sothat the uninterrupted supply of concrete to the job site is materiallyassured.
 3. A portable concrete mixer unit for temporary holding ofmixed concrete delivered to a job site which comprises: a vehicleincluding a frame, wheels for transport to and ground-stabilizing legsfor stationary positioning at the job site, a concrete mixing drumsupported by said frame for rotation on an inclined axis and having anupper open end at one end of the vehicle, said drum internally havingspiral blades which extend to said drum opening and define a smallercentral charging opening, power means carried by the vehicle andconnected to said drum to rotate the latter in one direction whichcauses the blades to push the drum contents to the lower closed endthereof and in the other direction to push the contents towArd and outof the upper open end thereof, a charging hopper for said drum carriedby said frame and having its spout extending into said smaller centralopening of the drum, an inclined power-driven conveyor carried by saidvehicle frame and having a receiving hopper disposed at the other end ofthe vehicle to receive mixed concrete as from a delivery truck, saidconveyor extending longitudinally over said drum and having itsdischarge trajectory directed into said charging hopper, and an inclineddischarge chute pivotally supported by said frame on a vertical axisbeneath said charging hopper and drum opening so that its upper endremains positioned to receive concrete therefrom and so that its lowerend may be variously positioned to deliver by gravity the concrete intoa receiving bucket or the like positioned within reach of the chute. 4.The unit of claim 3 wherein the conveyor includes parallel frameextensions which support the receiving hopper beyond the end of thevehicle frame and said receiving hopper and the projecting portion ofthe conveyor are retractable as required for transport or to allowtrucks to move past the end of the unit.
 5. The invention of claim 3wherein the vehicle comprises a conventional semitrailer.
 6. Theinvention of claim 3 wherein the conveyor is demountable from saidvehicle frame such that the unit may be used to deliver concrete as inthe manner of a truck mixer.